The Network Statistics monitor uses Simple Network Management Protocol (SNMP) to query a device to collect data on three device protocols, Internet Protocol (IP), Transmission Control Protocol (TCP), and User Datagram Protocol (UDP) and alerts you when configured thresholds are met or exceeded by determining the rate-of-change for an OID, or the difference between the current poll value and the last poll value for an OID. With the exception of the tcpCurrEstab threshold, all thresholds used in the Network Statistics Monitor are rate-of-change monitors.
Tip: When configuring a threshold, it is helpful to copy the OID from the parameter description listed on this dialog after you select a parameter. Paste this OID into the Object ID box in the SNMP MIB Walker (ANALYZE > Tools > SNMP MIB Walker), then click Walk. After the walk scan is complete, note the value listed. Perform several more walk scans, noting the value after each scan completes. These values illustrate how much this particular value may change over the course of several queries. Use these values as guidelines when configuring a threshold for the Network Statistics Monitor. You can also use the monitor Test function as an alternative to the SNMP MIB walker.